Sunshine-to-fuel: Demonstration of coupled photovoltaic-driven biomethanation operation, process, and techno-economical evaluation

TY - JOUR

T1 - Sunshine-to-fuel:

T2 - Demonstration of coupled photovoltaic-driven biomethanation operation, process, and techno-economical evaluation

AU - Sieborg, Mads Ujarak

AU - Engelbrecht, Nicolaas

AU - Ottosen, Lars Ditlev Mørck

AU - Kofoed, Michael Vedel Wegener

PY - 2024/1

Y1 - 2024/1

N2 - The accelerating green transition envisions large shares of renewable intermittent power supplies, which challenges the balancing of the grid. A promising approach to long-term storage is the power-to-X technology of biomethanation. This study developed an operating model for ex situ biomethanation in a trickle bed reactor (TBR) based on daily photovoltaic (PV) solar generation profiles from the California Flats solar cell park and demonstrated long-term discontinuous biomethanation of raw biogas. The TBR was operated discontinuously for 29 days, where biomethane admissible for natural gas grid injection could be achieved within a ramp-up time of < 16 min after an adaptation period of 6 days with a purity of < 2 % hydrogen and > 97.5 % biomethane. The shutdown periods demonstrated a continuous digestion of accumulated acids and biomass. Therefore, shutting off the hydrogen addition could synergistically be employed as a clean-in-place procedure, where ∼60 % of the accumulated volatile fatty acids were converted during 12 h of standby. The TBR performance was subsequently used to evaluate the economic feasibility of integrating biomethanation to convert and store solar PV energy. The levelized cost of production of grid-quality biomethane by a small commercial biomethanation system, subject to solar PV energy (28 MWh e d −1), was found to be 147.84 $ (MWh CH4 HHV) −1 in a 2030 scenario.

AB - The accelerating green transition envisions large shares of renewable intermittent power supplies, which challenges the balancing of the grid. A promising approach to long-term storage is the power-to-X technology of biomethanation. This study developed an operating model for ex situ biomethanation in a trickle bed reactor (TBR) based on daily photovoltaic (PV) solar generation profiles from the California Flats solar cell park and demonstrated long-term discontinuous biomethanation of raw biogas. The TBR was operated discontinuously for 29 days, where biomethane admissible for natural gas grid injection could be achieved within a ramp-up time of < 16 min after an adaptation period of 6 days with a purity of < 2 % hydrogen and > 97.5 % biomethane. The shutdown periods demonstrated a continuous digestion of accumulated acids and biomass. Therefore, shutting off the hydrogen addition could synergistically be employed as a clean-in-place procedure, where ∼60 % of the accumulated volatile fatty acids were converted during 12 h of standby. The TBR performance was subsequently used to evaluate the economic feasibility of integrating biomethanation to convert and store solar PV energy. The levelized cost of production of grid-quality biomethane by a small commercial biomethanation system, subject to solar PV energy (28 MWh e d −1), was found to be 147.84 $ (MWh CH4 HHV) −1 in a 2030 scenario.

KW - Biological methanation

KW - Intermittent operation

KW - Methanogens

KW - Power-to-x

KW - Solar cells

KW - Trickle bed reactors

UR - http://www.scopus.com/inward/record.url?scp=85175558799&partnerID=8YFLogxK

U2 - 10.1016/j.enconman.2023.117767

DO - 10.1016/j.enconman.2023.117767

M3 - Journal article

SN - 0196-8904

VL - 299

JO - Energy Conversion and Management

JF - Energy Conversion and Management

M1 - 117767

ER -